(function(win, tcf) {
	var doc = win.document;
	var docEl = doc.documentElement;
	var metaEl = doc.querySelector('meta[name="viewport"]');
	var dpr = 0;
	var scale = 0;
	var handler = null;

	var flexible = tcf.flexible || (tcf.flexible = {});

	//将根据已有的meta标签来设置缩放比例
	if (metaEl) {
		var match = metaEl.getAttribute('content').match(/initial\-scale=([\d\.]+)/);
		if (match) {
			scale = parseFloat(match[1]);
			dpr = parseInt(1 / scale);
		}
	}
	//如果没有设置，那么会自动添加meta viewport的设置
	if (!dpr && !scale) {
		var isAndroid = win.navigator.appVersion.match(/android/gi);
		var isIPhone = win.navigator.appVersion.match(/iphone/gi);
		var devicePixelRatio = Math.floor(win.devicePixelRatio) || 1;
		if (isIPhone) {
			if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
				dpr = 3;
			} else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
				dpr = 2;
			} else {
				dpr = 1;
			}

		} else {

			dpr = 1;
		}

		scale = 1 / dpr;
	}



	if (!metaEl) {
		metaEl = doc.createElement('meta');
		metaEl.setAttribute('name', 'viewport');
		metaEl.setAttribute('content', 'initial-scale=' + scale + ', maximum-scale=' + scale + ', minimum-scale=' + scale + ',user-scalable=no');
		if (docEl.firstElementChild) {
			docEl.firstElementChild.appendChild(metaEl);
		} else {
			var wrap = doc.createElement('div');
			wrap.appendChild(metaEl);
			doc.write(wrap.innerHTML);
		}
	}

	docEl.setAttribute('data-dpr', dpr);

	var setFontSize = function() {
		var width = docEl.getBoundingClientRect().width || innerWidth;

		var rem = width / 10;

		rem = Math.max(rem, 32);

		docEl.style.fontSize = rem + 'px';
		flexible.width = width;
		flexible.rem = win.rem = rem;
	};

	['resize', 'orientationchange'].forEach(function(item) {
		win.addEventListener(item, function(e) {
			clearTimeout(handler);
			handler = setTimeout(setFontSize, 300);
		}, false);
	})

	win.addEventListener('pageshow', function(e) {
		if (e.persisted) {
			clearTimeout(handler);
			handler = setTimeout(setFontSize, 300);
		}
	}, false);

	if (doc.readyState === 'complete') {

		doc.body.style.fontSize = 12 * dpr + 'px';

	} else {
		doc.addEventListener('DOMContentLoaded', function(e) {
			doc.body.style.fontSize = 12 * dpr + 'px';

		}, false);
	}

	setFontSize();

	flexible.dpr = win.dpr = dpr;
	flexible.setFontSize = setFontSize;
	flexible.rem2px = function(d) {
		var val = parseFloat(d) * this.rem;
		if (typeof d === 'string' && d.match(/rem$/)) {
			val += 'px';
		}
		return val;
	}
	flexible.px2rem = function(d) {
		var val = parseFloat(d) / this.rem;
		if (typeof d === 'string' && d.match(/px$/)) {
			val += 'rem';
		}
		return val;
	}

}(window, window['tcf'] || (window['tcf'] = {})))